Rotary machine apex seal

ABSTRACT

A rotary machine apex seal arrangement having a pair of seal members that are pivotally mounted on a pin on the machine&#39;&#39;s rotor and are biased by chamber pressure, centrifugal force and a compression spring therebetween to contact the machine&#39;&#39;s internal peripheral wall to provide leading and trailing seals.

United States Patent [191 Klomp 1 ROTARY MACHINE APEX SEAL [75] Inventor: Edward D. Klomp, Mt. Clemens,

Mich.

[731 Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Feb. 9, 1972 211 AppL No.2 224,883

[52] U.S.Cl ..418/l17,418/118,418/122 [51] Int. Cl. FOlc 19/02, F03c 3/00, F040 27/00 [58] Field of Search.... 418/117, 118,122,123, 124

[56] References Cited UNITED STATES PATENTS 3,689,208 9/1972 Nebel"; 418/268 X Feb. 26, 1974 FOREIGN PATENTS OR APPLICATIONS 1,347,541 11/1963 France 418/118 1,189,789 3/1965 Germany 418/118 Primary Examiner-Carlton R. Croyle Assistant ExaminerRichard E. Gluck Attorney, Agent, or Firm-R. L. Phillips 5 7] ABSTRACT A rotary machine apex seal arrangement having a pair of seal members that are pivotally mounted on a pin on the machines rotor and are biased by chamber pressure, centrifugal force and a compression spring therebetween to contact the machines internal peripheral wall to provide leading and trailing seals.

4 Claims, 3 Drawing Figures ROTARY MACHINE APEX SEAL This invention relates to rotary machine apex seals and more particularly to rotary machine apex seals providing labyrinth sealing.

In rotary machines such as rotary combustion engines, pumps, compressors, and the like, wherein a seal arrangement is provided at each rotor apex to continuously sealingly engage an internal peripheral wall in the machine to separate the machines working chambers which rotate with the rotor, the demands on such sealing are greater than those on the sealing in reciprocating piston engines since in the former there may be leakage between the working chambers whereas in the latter leakage is normally to thecrankcase. Furthermore, in such rotary machines, the angle between the apex seal and the peripheral wall normally changes during rotor rotation because of the irregular curvature of this wall with the result that conventional type labyrinth sealing which will remain efficient during rotation and also as sea] wear occurs is not normally readily adaptable to such angle change.

The present invention is disclosed in a rotary machine having a rotor housing with an internal peripheral wall wherein a rotor is rotatable relative to this wall and sealing is normally provided between each rotor apex and the wall to separate the machines working chambers which rotate with the rotor relative to the housing. Each of the apex seal arrangements according to the present invention comprises a pair of seal members having circular arc hub portions which are sealingly engaged with and supported by a circular arc surface in each rotor apex. The hub portions of these seal members are also pivotally mounted on a pin extending therebetween and are biased by a compression spring to engage the sealing end of a radial extension of each of these seal members with the peripheral wall. Furthermore, the angularity and location 'of the center of gravity of the radial extensions of the seal members is determined so that chamber pressure and centrifugal force also act on the seal members to force their pivoting in opposite directions about the pin to maintain sealing engagement as the rotor rotates.

An object of the present invention is to provide a new and improved rotary machine apex seal.

Another object is to provide in a rotary machine apex seal arrangement a pair of seal members which are pivotally mounted and are biased by chamber pressure and centrifugal force to pivot in opposite directions to contact the machines inner peripheral wall to provide leading and trailing seals.

Another object is to provide in a rotary machine a rotor apex seal arrangement wherein a spring biases a pair of seal members to pivot in opposite directions to sealingly engage the machines inner peripheral wall to provide leading and trailing seals and wherein the two seal members are also biased to such engagement by chamber pressure and centrifugal force.

Another object is to provide an apex seal arrangement for a rotary machine wherein labyrinth type sealing is effected by a pair of seal members which are mounted for relative pivotal movement about an axis fixed with respect to the rotor to sealingly engage the machines inner peripheral wall to provide leading and trailing seals which follow the contour of the wall as the rotor rotates with such pivotal seal member movement effected by chamber pressure, centrifugal force and/or a spring force.

These and other objects of the present invention will become more apparent from the following description and accompanying drawing in which:

FIG. 1 is a transverse sectional view of a rotary machine having apex seal arrangements according to the present invention.

FIG. 2 is an enlarged view of one of the apex seal arrangements in FIG. 1.

FIG. 3 is an exploded view of the apex seal arrangement of FIG. 2.

The apex seal arrangement according to the present invention is for use in rotary machines including rotary combustion engines, compressors, pumps, and the like. Referring to FIG. 1, the rotary machine may, for example, be an internal combustion engine of the Wankel type comprising a stationary outer body or housing having a rotor cavity 12 that is defined by an inwardly facing peripheral wall 14 and a pair of axially spaced side walls 16 of which only one is shown. In the Wankel engine the peripheral wall 14 is in the shape of a twolobed epitrochoid or a curve parallel thereto and a rotor 18 having the general shape of a triangle with three faces 20 is mounted in the rotor cavity 12 on an eccentric 21 of an output shaft 22. The output shaft 22 is joumaled on opposite sides of the rotor 18 in the housing 10 with its axis 23 aligned with the axis of cavity l2 and the eccentrics axis 24 offset from and parallel thereto. Gearing, not shown, between the housing 10 and the rotor 18 enforces a fixed, cyclic relation between the rotor and output shaft and the rotor faces cooperate with the peripheral wall and with the end walls to define three variable volume combustion or working chambers 25. Chambers 25 are spaced around the rotor and move with the rotor within the housing as the rotor rotates about its axis 24 while planetating with respect to the output shaft axis 23. A fuel-air inlet passage 26 provides for admission of fuel-air mixture to each chamber, a spark plug 27 ignites the mixture, and an exhaust passage 28 provides for exhaust of products of combustion from each chamber as the rotor rotates with each chamber undergoing intake, compression, expansion and exhaust to provide a power phase for each revolution of the engine. output. The structure thus far described is conventional and operates efficiently assuming there is effective sealing between the chambers of the engine.

An apex seal arrangement 30 according to the present invention is mounted on each of the rotors three apexes to provide sealing between the adjoining chambers 25 of the engine. Each apex seal arrangement 30 is generally of the labyrinth type and as best shown in FIGS. 2 and 3 comprises a pair of seal members 32 and 34 of identical shape. Each of the seal members 32 and 34 has a circular arc hub or base portion 36 having a large diameter convex circular are surface 38 slidably supported by and sealingly engaged with a concave circular are surface 40 of a groove formed in an apex of the rotor 18, the circular arc surface 40 extending axially the width of the rotor 18 and the length of the seal members in this direction extending from one of the engine side walls 16 to the other with sufficient end clearance therebetween. Sealing between the rotor 18 and the. housing side walls 16 is provided by side sealing strips 41 which are mounted in accommodating side seal grooves in the sides of the rotor and extend between and sealingly abut with the surfaces 38 of the seal members 32 and 34 at adjacent apexes. Each of the circular arc hub portions 36 of the seal members 32 also have a smaller diameter convex circular arc surface 42 which is slidably supported by and sealingly engaged with a circular pin 44 extending axially the width of the rotor. The hub portions 36 of the seal members 32 and 34 are located on opposite sides of the pin 44 and a wave spring 46 is located in the space between the pin 44 and the rotor surface 40. The spring 46 extends axially the width of the rotor and engages the inner ends 48 of the seal members 32-and 34 to urge them to pivot in opposite directions about the axis 45 of the pivot pin 44 to yieldingly hold rounded ends 50 of these seal members in contact with the machines inner peripheral wall 14. Furthermore, the arc of the groove 40 is made greater than 180 as clearly seen in FIG. 3 so that the apex seal arrangement is thereby retained on the rotor apex prior to assembly of the rotor in the machine.

In addition to the springbias, the seal members 32 and 34 are biased to scaling engagement by chamber pressure and centrifugal force during engine operation by each round seal 50 being formed on a finger portion 52 that extends radially from the hub portion 36 of the seal members 32 and 34. Each finger portion 52 is located at an acute angle measured on the nonworking chamber side of the seal member with respect to the peripheral wall 14 with its center of gravity 54 located on this chambers side of a plane 56 normal to the peripheral wall 14 and passing through the pin axis 45 so that centrifugal force urges each seal member about the pivot pin axis 45 in the direction that engages the seal end 50 with the peripheral wall. Furthermore, each finger portion 52 has a substantial chamber side area 58 between the rotor 18 and peripheral wall 14 exposed to the respective chamber so that chamber pressure also provides a substantial force to urge each seal member to sealingly engage the peripheral wall.

In the operation of the apex seal arrangements, and with the rotor 18 rotating in the direction of the arrow indicated in FIG. 1, each seal member 32 acts as the leading seal and the other seal member 34 acts as the trailing seal at each rotor apex to prevent leakage between the adjoining leading and trailing chambers. As the rotor 18 revolves and clearance between the rotor 18 and the peripheral wall 14 varies, the seal members 32 and 34 are forced to rotate about the pin 44 to maintain sealing contact with the peripheral wall by chamber pressure, centrifugal force, and/or spring 46, it being understood that the spring 46 also acts to maintain the seal members in sealing contact with the peripheral wall to provide static chamber sealing for engine starting. During engine running there is a varying pressure differential between adjoining chambers and as a result there will be a varying pressure differential across each finger to assist in maintaining sealing engagement. The pressure differentials across the finger portions of the seal members 32 and 34 do not reach their minimum simultaneously, one always being larger than the other, and thus the seal member experiencing the larger pressure bias provides the primary sealing function while the other seal member having the small pressure bias is maintained in contact with the peripheral wall by centrifugal force and the spring which is continuously under compression. Thus, the normal force between the fingers and the peripheral wall is determined by the angle 0 and the size of the chamber area 58 in addition to the spring force which parameters are all readily variable to meet specific seal load requirements. With regard to determination of the seal angle 9, the tangent of this angle for each leading seal 32 is made greater than the coefficient of friction between the seal and the peripheral wall at all locations to prevent wedging of the seal member against this wall as the rotor rotates.

The above described embodiment is illustrative of the invention which may be modified within the scope of the appended claims I claim:

1. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall, and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a circular arc hub portion and a. finger portion extending radially therefrom having a sealing edge, both said hub portion and said finger-portion extending substantially the axial length of said rotor, said rotor having a circular are surface greater than extending axially thereof, each of said seal members having an outer circular are surface extending substantially the axial length of said rotor and being slidably supported by and continuously sealingly engaged with said circular are surface on said rotor, a pivot pin also extending substantially the axial length of said rotor, each of said hub portions of said seal members further having a circular inner are surface slidably supported by and continuously sealingly engaged with only a corresponding circular arc portion of said pivot pin, said circular arc hub portions terminating in respective spaced inner ends which in conjunction with said pin and said rotor circular are surface define an arcuate cavity therebetween, means in said cavity engaging said hub inner ends for biasing said seal members to pivot in opposite directions upon said pivot pin to effect continuous engagement of the sealing edges of said seal members with said peripheral wall.

2. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall, and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a circular arc hub portion and a finger portion extending radially therefrom having a sealing edge, both said hub portion and said finger portion extending substantially the axial length of the said rotor, said rotor having a concave circular arc surface greater than 180 extending axially thereof, each circular arc hub portion of said seal members having an outer convex circular are surface extending substantially the axial length of said rotor and continuously sealingly engaged with and supported for sliding movement by said concave circular are surface on said rotor, a pivot pin also extending substantially the axial length of said rotor, each said hub portion of said seal members further having an inner concave circular arc surface of smaller diameter than its convex circular are surface continuously engaged with and supported for sliding movement by only a corresponding circular arc portion of said pivot pin, said circular arc hub portions terminating in respective spaced inner ends which in conjunction with said pin and said rotor circular are surface define an arcuate cavity therebetween, a spring mounted between said pivot pin and said concave circular are surface of said rotor in said arcuate cavity and engaging both inner ends of said hub portions of said seal members and being prestressed to bias said seal members to pivot in opposite directions about said pivot pin to continuously engage the sealing edges of said sealing members with said peripheral wall.

3. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a circular arc hub portion and a finger portion extending radially therefrom having a sealing edge, both said hub portion and said finger portion extending substantially the axial length of said rotor, sa'id rotor having a concave circular are surface greater than 180 extending axially thereof, each said hub portion of said seal members having an outer convex circular arc surface extending substantially the axial length of said rotor and continuously sealingly engaged with and supported for sliding movement by said concave circular are surface on said rotor, a pivot pin also extending substantially the axial length of said rotor, each said hub portion of said seal members further having an inner concave circular are surface of smaller diameter than its convex circular are surface continuously sealingly engaged with and supported for sliding movement by only a corresponding circular arc portion of said pivot pin, said circular arc hub portions terminating in respective spaced inner ends which in conjunction with said pin and said rotor circular are surface define an arcuate cavity therebetween, means in said arcuate cavity engaging the inner ends of said hub portions urging said seal members to pivot in opposite directions about said pivot pin to continuously engage the sealing edges of said sealing members with said peripheral wall.

4. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall and cooperating with said wall to define adjoining chambers that rotate with said rotor, and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a circular arc hub portion and a finger portion extending radially therefrom having a sealing edge, both said hub portion and said finger portion extending substantially the axial length of said rotor, said rotor having a concave circular arc surface greater than extending axially thereof, each said hub portion of said seal members having an outer convex circular are surface extending substantially the axial length of said rotor and continuously sealingly engaged with and supported for sliding movement by said concave circular are surface on said rotor, a pivot pin also extending substantially the axial length of said rotor, each said hub portion of said seal members further having an inner concave circular are surface of smaller diameter than its convex circular are surface continuously sealingly engaged with and supported for sliding movement by only a corresponding circular arc portion of said pivot pin, s'aid circular arc hub portions terminating in respective spaced inner ends which in conjunction with said pin and said rotor circular are surface define an arcuate cavity therebetween, said seal members arranged relative to each. other about said pin so that said sealing edges are engaged with said peripheral wall on sufficient movement of said seal members in opposite seal engaging directions about said pivot pin, a spring mounted between said pivot pin and said concave circular are surface of said rotor in saidarcuate cavity and engaging both inner ends, said hub portions of said seal members and prestr essed to bias said seal members to pivot in opposite directions about said pivot pin to continuously engage the sealing edges of said sealing members with said peripheral wall, each said finger portion having an acute angle with said peripheral wall and a center of gravity located relative to said pivot pin so that centrifugal force urges movement of the respective seal member in its seal engaging direction, each said finger portion also having a side area exposed to only one of said chambers so that chamber pressure also urges move- I ment of the respective seal member in its seal engaging direction. 

1. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall, and seal means for continuously providing sealing between said peripheral wall and said rotor as sAid rotor rotates comprising a pair of seal members each having a circular arc hub portion and a finger portion extending radially therefrom having a sealing edge, both said hub portion and said finger portion extending substantially the axial length of said rotor, said rotor having a circular arc surface greater than 180* extending axially thereof, each of said seal members having an outer circular arc surface extending substantially the axial length of said rotor and being slidably supported by and continuously sealingly engaged with said circular arc surface on said rotor, a pivot pin also extending substantially the axial length of said rotor, each of said hub portions of said seal members further having a circular inner arc surface slidably supported by and continuously sealingly engaged with only a corresponding circular arc portion of said pivot pin, said circular arc hub portions terminating in respective spaced inner ends which in conjunction with said pin and said rotor circular arc surface define an arcuate cavity therebetween, means in said cavity engaging said hub inner ends for biasing said seal members to pivot in opposite directions upon said pivot pin to effect continuous engagement of the sealing edges of said seal members with said peripheral wall.
 2. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall, and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a circular arc hub portion and a finger portion extending radially therefrom having a sealing edge, both said hub portion and said finger portion extending substantially the axial length of the said rotor, said rotor having a concave circular arc surface greater than 180* extending axially thereof, each circular arc hub portion of said seal members having an outer convex circular arc surface extending substantially the axial length of said rotor and continuously sealingly engaged with and supported for sliding movement by said concave circular arc surface on said rotor, a pivot pin also extending substantially the axial length of said rotor, each said hub portion of said seal members further having an inner concave circular arc surface of smaller diameter than its convex circular arc surface continuously engaged with and supported for sliding movement by only a corresponding circular arc portion of said pivot pin, said circular arc hub portions terminating in respective spaced inner ends which in conjunction with said pin and said rotor circular arc surface define an arcuate cavity therebetween, a spring mounted between said pivot pin and said concave circular arc surface of said rotor in said arcuate cavity and engaging both inner ends of said hub portions of said seal members and being prestressed to bias said seal members to pivot in opposite directions about said pivot pin to continuously engage the sealing edges of said sealing members with said peripheral wall.
 3. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a circular arc hub portion and a finger portion extending radially therefrom having a sealing edge, both said hub portion and said finger portion extending substantially the axial length of said rotor, said rotor having a concave circular arc surface greater than 180* extending axially thereof, each said hub portion of said seal members having an outer convex circular arc surface extending substantially the axial length of said rotor and continuously sealingly engaged with and supported for sliding movement by said concave circular arc surface on said rotor, a pivot pin also extending substantially the axial length of said rotor, each said hub portioN of said seal members further having an inner concave circular arc surface of smaller diameter than its convex circular arc surface continuously sealingly engaged with and supported for sliding movement by only a corresponding circular arc portion of said pivot pin, said circular arc hub portions terminating in respective spaced inner ends which in conjunction with said pin and said rotor circular arc surface define an arcuate cavity therebetween, means in said arcuate cavity engaging the inner ends of said hub portions urging said seal members to pivot in opposite directions about said pivot pin to continuously engage the sealing edges of said sealing members with said peripheral wall.
 4. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall and cooperating with said wall to define adjoining chambers that rotate with said rotor, and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a circular arc hub portion and a finger portion extending radially therefrom having a sealing edge, both said hub portion and said finger portion extending substantially the axial length of said rotor, said rotor having a concave circular arc surface greater than 180* extending axially thereof, each said hub portion of said seal members having an outer convex circular arc surface extending substantially the axial length of said rotor and continuously sealingly engaged with and supported for sliding movement by said concave circular arc surface on said rotor, a pivot pin also extending substantially the axial length of said rotor, each said hub portion of said seal members further having an inner concave circular arc surface of smaller diameter than its convex circular arc surface continuously sealingly engaged with and supported for sliding movement by only a corresponding circular arc portion of said pivot pin, said circular arc hub portions terminating in respective spaced inner ends which in conjunction with said pin and said rotor circular arc surface define an arcuate cavity therebetween, said seal members arranged relative to each other about said pin so that said sealing edges are engaged with said peripheral wall on sufficient movement of said seal members in opposite seal engaging directions about said pivot pin, a spring mounted between said pivot pin and said concave circular arc surface of said rotor in said arcuate cavity and engaging both inner ends, said hub portions of said seal members and prestressed to bias said seal members to pivot in opposite directions about said pivot pin to continuously engage the sealing edges of said sealing members with said peripheral wall, each said finger portion having an acute angle with said peripheral wall and a center of gravity located relative to said pivot pin so that centrifugal force urges movement of the respective seal member in its seal engaging direction, each said finger portion also having a side area exposed to only one of said chambers so that chamber pressure also urges movement of the respective seal member in its seal engaging direction. 